1. Field of the Invention
This invention relates to a current mirror sense amplifier and, more specifically, to a current mirror sense amplifier having a tri-state output.
2. Brief Description of the Prior Art
In a random access memory (RAM) that uses x8 or higher architecture, it is often necessary to share the data buses between input and output to reduce the number of buses in the circuit. Sharing of buses between input and output requires that the circuit sense amplifier be truly tri-state during the WRITE operation. Normally, this requirement is accomplished by using a pass gate between the sense amplifier and the data buses to isolate the output of the sense amplifier from the buses during a WRITE operation when data is being applied to the data buses by the input data driver. In such circuits, where the data bus is long, it is necessary to use large pass gates between the current mirror and the data buses. The pass gates are generally large in order to drive the data buses adequately and therefore take up a great deal of chip real estate. It is therefore desirable that the pass gates be eliminated.